Questions

The purpose of using insulin is to get the best management of blood sugar readings as close to normal blood sugar readings as possible to help avoid complications from diabetes.

People with Type 1 diabetes always require insulin injections in order to control blood sugar readings because they make little or no insulin.

‘prefer’ is a verb that is always followed by the preposition ‘to’ expressing choice or preference over something else. In this case choice of ‘this book’ over the ‘other’ one. ‘Than’ is used for comparing to options, ‘prefer to’ expresses choice. Correct expression will be ‘to that one’.

The error is in third part. Replace ‘good’ with ‘correct’. English is not good or bad, but it can be correct or incorrect. We can also say ‘All of them speak English well’, or ‘All of them speak fluent English’. The error remains in part c.