Fill in the blanks using appropriate articles:
Peru is _____ country in South America. _____ capital is Lima.
a) a , A
b) the , The
c) the , A
d) a , The

Hint: The rules to use articles are simple. “A” is used when the word starts with a consonant and we are referring to one out of many similar things. “An” is used when the word starts with a vowel. “The” is used when we are referring to a particular thing or a proper noun.

Complete answer:
a) a, A- "A capital is Lima" sounds like Peru has many capitals and one of them is Lima. Both the blanks will not use the article "a". Option a is wrong.
b) the The - "Peru is the country in South America" implies that Peru is the only country in South America when actually South America has a lot of countries and Peru is just one of those many countries. Thus, option b is also wrong.
c) the, A- The "the" is not to be used in the first blank for reasons already mentioned above. The same applies to the usage of "A" in the second blank.
d) a The - Peru is a country among many other countries in South America. We are referring to Peru as one of those countries. However, when we are talking about Lima as the capital, we are referring to a proper noun and therefore we use "The". We are referring to the capital of a particular country.
The correct option is option d.

Note:
“The” is used before anything which is just one in number or you refer to something particular. “The bag” means you are talking about one particular bag and not any bag. So don’t always restrict yourself to using “the” before proper nouns only.