Learner refers back to an earlier idea instead of repeating the noun, which is assessed under Coherence and Cohesion as well as Lexical Resource.
Preview · progress not saved — Chapter 1 is free
One paragraph, one noun, five appearances. Mark each one.
Two words can replace a whole sentence — as long as the reader knows which one.
This is the only sprint in the course where the fix makes your essay shorter.
Air pollution has increased every year since 2010. Air pollution is caused by cars and factories.
Air pollution has increased every year since 2010. This trend is driven by cars and factories.
Two words replaced two. But look at what this trend did that the repetition could not: it named the relationship between the sentences. The reader now knows sentence two is about the increase, not about pollution in general.
That is why this is assessed under Coherence and Cohesion as well as Lexical Resource. You are not just avoiding a repeated word — you are showing the examiner that your sentences are connected.
Every reference word points back at something. One of these points at nothing.

If you cannot draw the arrow, the reader cannot follow it.
Eight references. Six point somewhere exact — two point nowhere.
Terms
Definitions
Three checks. If you cannot point at the exact words, the reference has failed.
Chain 1
Rents in the capital rose every year for a decade. This trend has only recently slowed.
Can you point at exactly what "this trend" replaces?
So this reference is:
Chain 2
The council raised parking charges and the bus company cut evening services. This angered local residents.
Can you point at exactly what "this" replaces?
So this reference is:
The repair is to add a noun after "this", giving:
Chain 3
The city can either build more homes or restrict foreign buyers. The latter could begin within a year.
How many options came before it?
So "the latter" points at:
One noun, five appearances. Replace three and keep every reference clear.
Air pollution
Air pollution is a serious problem in most large cities. (first mention — this one stays)
It is caused mainly by traffic and by industry. have grown together in every expanding city over the past thirty years. (was: these two things)
Measurements show that air pollution has risen every year since 2010. has continued despite three separate government programmes. (was: this rise in air pollution)
The city has responded by building cycle lanes and by restricting older vehicles in the centre. were introduced in the same year but have had very different results. (was: these actions)
Even so, air pollution remains above the safe level in most districts. (final mention — this one stays, to re-anchor the reader)