Join the sentences using a suitable connector-
I was bruised. I completed the race.
a) But
b) Since
c)While
d) And

Hint: Conjunctions grammatically join two clauses (independent or dependent, depending on the conjunction) so that it reads as one sentence.

Complete answer:
 Connectors are used between two separate sentences. The usage of coordinating connectors give equal value to the two elements that they coordinate. They must be placed between the two elements that they coordinate. We have to choose the most suitable conjunction for the given phrases.
Now, let us examine all the given options to find out the correct answer :
Option ‘a’ is But. It is a conjunction that is used to introduce a phrase or clause contrasting with what has already been mentioned.
Option ‘b’ is Since. It is a preposition which means - in the intervening period between (the time mentioned) and the time under consideration, typically the present.
Option ‘c' is While. It is a conjunction which means - During the time that; at the same time as. It may also mean – whereas.
Option ‘d’ is And. It is a conjunction that is used to connect words of the same part of speech, clauses, or sentences, that are to be taken jointly.
As we have analyzed all the given options, we can easily figure out the correct answer. Here, the word that will join the two given sentences correctly is – but. The complete sentence would be – I was bruised but I completed the race. Hence, option ‘a’ is the correct option.

Note:
 Unlike coordinating conjunctions, subordinate conjunctions can often come first in a sentence. This is because of the nature of the relationship between the dependent and the independent clause.