In which sentence does the verb number need to be changed in order to agree with the number of the subject?

a. my aunt and uncle usually sends me a picture postcard when they travel.

b. either samuel or kevin is doing his next report on careers in biology.

c. art, math, and science need to be studied by architecture students.

d. the oak tree and the maple tree in the front yard shade the porch.

A. My aunt and uncle usually sends me a picture postcard when they travel.

Explanation:

The subject is My aunt and uncle. This phrase can be replaced with the pronoun they because we have two people here who send me a postcard. So  the verb number needs to be changed in order to agree with the number of the subject: it should be send, not sends.  

In other words, use a plural verb with two or more subjects when they are connected by and.    

author – information on the internet with a listed author is one indication of a credible site. the fact that the author is willing to stand behind the information presented (and in some cases, include his or her contact information) is a good indication that the information is reliable.

date – the date of any research information is important, including information found on the internet. by including a date, the website allows readers to make decisions about whether that information is recent enough for their purposes.

sources – credible websites, like books and scholarly articles, should cite the source of the information presented.

domain – some domains such as .com, .org, and .net can be purchased and used by any individual. however, the domain .edu is reserved for colleges and universities, while .gov denotes a government website. these two are usually credible sources for information (though occasionally a university will assign a .edu address to each of its students for personal use, in which case use caution when citing). be careful with the domain .org, because .org is usually used by non-profit organizations which may have an agenda of persuasion rather than education.

site design – this can be very subjective, but a well-designed site can be an indication of more reliable information. good design make information more easily accessible.

writing style – poor spelling and grammar are an indication that the site may not be credible. in an effort to make the information presented easy to understand, credible sites watch writing style closely.

if you want me to check your answer i agree with what you put. i read the story