Answer:a. Teaching them in contrast with other tenses
Explanation:It is mostly likely that one learns better when all the tenses are laid before their eyes in order to be able to read the differences and compare them at the same time .
It is most likely to grasp the tenses when one can see how they move from one tense to another so that they can be able to establish what changes in a sentence when that happens.
For example one can be able to see how the verb changes from past tense to past participle tense or how it changes from present to present continuous tense , the changes in a verb has to be seen together at the same time in order to grasp the differences that occur as one changes from one tense to another .