A table ordered by age from oldest to youngest.单项选择题

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Suppose you have a data frame df about everyone enrolled in a class with 30 students. As it just so happens, no two students in the class share the same last name. In other words, there is no more than one student with the same last name in the class. There are three columns in the data frame, which are all character data type: UBC_ID, lastname, and firstname. Assume that UBC_ID can uniquely identify each person in this dataset. That is, each student has a unique UBC_ID. You open the dataset, and then run the following code: dfa <- df %>% arrange(lastname, firstname) Right after that, you run the following line of code: dfb <- df %>% arrange(lastname, UBC_ID) [ Select ] True False Not enough information  The order of the observations in dfa is the same as the order of the observations in dfb. If not enough information is provided, choose “not enough information”.  

Use rand_vec vector created above. Remember v[i] will allow to access the i-th element of vector v. First, create a new vector called sorted_rand_vec by sorting rand_vec in descending order. Then return the 55th element of the sorted vector (i.e., sorted_rand_vec) by rounding the value to its 3 decimal place. Hint: Use ?sort to see the default order of sort function. That is, you need to figure out whether sort would order the elements in ascending (i.e. increasing) or descending (i.e. decreasing) order. If the default is not what you want, you need to specify that particular argument as to what you want.  

Question at position 8 An excess of growth hormone (GH) before puberty can result in the development ofgigantism.Graves' disease.acromegaly.pituitary dwarfism.Clear my selection

Question at position 6 The most abundant supporting cells in the central nervous system are called Question Blank 1 of 1[input].

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