The correct answer is option (D):
ubiquitous … comfortable
The correct answer is "ubiquitous … comfortable" because it best reflects the relationship between the invention of the cell phone and its impact on our lives.
"Ubiquitous" means existing or being everywhere at the same time. Cell phones have become incredibly widespread, a common sight in almost every aspect of modern life. This widespread availability aligns well with the sentence's beginning, describing the cell phone.
"Comfortable" aligns with the second part of the sentence: "making our lives comfortable and happy". While cell phones can certainly bring happiness, the idea of increasing comfort is also fitting. Cell phones make our lives comfortable by providing constant access to information, communication, entertainment, and other conveniences.
The other options don't fit the sentence's intended meaning as well:
* "Popular...blissful": While cell phones are popular, "blissful" is an exaggeration and doesn't capture the overall impact cell phones have on our everyday lives.
* "Modern...stressful": Modern is a fitting description of a cell phone, but the sentence suggests that technology should be making our lives better, not stressing us.
* "Portable...pleasant": Portable is a good characteristic of a cell phone, but pleasant does not quite match the tone of the sentence, which aims to highlight the general impact of the cell phone on our daily life.
* "Effective...joyful": While a cell phone can be effective, "joyful" is not a word that appropriately highlights the general advantages of cell phones.
Therefore, "ubiquitous ... comfortable" is the most logical and contextually appropriate answer.