<span>Science is a practice of gaining comprehension of the nature of materials and phenomena by gathering and evaluating evidence. A scientific study is based on an hypothesis, a theory of causality. As the body of scientific knowledge increases, the design of scientific studies is informed by previous discoveries.</span>
The right option is; unsecured loan
Zachary's student loans are an example of unsecured loan.
An unsecured loan is a type of loan that is given and supported only by the borrower’s reliability without being protected by any collateral. If an individual is unable to pay the loan, the lender cannot take his or her property. Types of unsecured loan include student loans, credit cards and personal loans.
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
